"There's an old saying my late grandma taught me. When you're ten, they call you a prodigy. When you're fifteen, they call you a genius. Once you hit twenty, you're just an ordinary person." — Haruka Nanase, Free!

Nearly every high achieving athlete that didn't use performance enhacing drugs or just hasn't been caught, I haven't watched the Death Note series (only the movies) and I don't know how long it took before he was caught but Lance Armstrong lasted for seven years, give or take one or two.

The animal thing wasn't her fault, it was the animals who were instinctively scared of her and she did show restraint otherwise she would had killed Zenkichi easy but instead she only roughed him up enough.

She was trying anything, no matter how stupid because she had no other ideas.

Nah, she kept hitting them until she stopped attacking her, the only time where she didn't show any restraint was against Kumagawa when they were younger and Unzen, after that she stopped every time, well and Zenkichi, hell she didn't even attack the chick who stabbed Zenkichi in the Jet Black arc when even Naze was about

Mate, you're taking this way too deep and bringing up subjects no one was even talking about just to try and make yourself look intellectual. I've known you for all of the 45 minutes I've spent here discussing AoT and in that time I've seen you try and fail at this concept multiple times. A biscuit for your efforts, but you need a different hobby. Or at least a different playground to practice it.

He was an idiot at properly covering his tracks and avoiding suspicion, as everything he did was uncovered by L, Mello, and Near, except for that he hid the Death Note in his desk. He also drew attention to himself by accessing police files.

He covered his tracks so well that nearly everything he did was figured out by L almost immediately after he did them. And 3 or 4, which is a pretty short time in the world of crime.
And he was in no way perfect.
They can't because authors realize that nobody likes someone that is perfect in every way and that they won't make as much money than if they made someone with flaws.